1. Field of Invention
This invention relates to the use of nanostructured materials and aluminum composite materials in musical instrument construction.
2. Prior Art
This invention relates to the material composition of vibrating components in musical instruments. A class of instruments herein specified, are those whose initial tone is produced by a vibrating string. Sound from this string is amplified by the sympathetic vibration of one or more soundboards. Examples of such instruments include bowed instruments of the violin family, plucked instruments of the guitar family, as well as keyboard instruments such as the piano. It is desirable for soundboards to be made from a material that has lasting strength and durability as well as favorable acoustical properties.
In musical instruments where a soundboard is required, the quality or “color” of ultimate tone produced, as also its relative amplitude, depends to a large measure on the inherent physical properties of the material composing the soundboard(s), apart from mere structure. At present, the dominating practice is to construct such soundboards of wood, the selection of which is comparatively limited, as most woods are unsuited for the purpose. The cost of these instruments is relatively high due to the skilled craftsmanship involved and individual attention needed to produce articles of wood. There are also high materials cost, as the preferred woods, like spruce, maple, and mahogany, besides scarcity, must be carefully cut and patiently dried, often for years, before use. Wood laminate construction is cheaper than solid wood, but is subject to separation of the glued layers. Wood altogether has inherent irregularities that can result in unpredictable, undesirable, and irregular sound qualities of the finished instrument. Instruments made with wooden soundboards can also be damaged by a number of physical elements.
While some instrument soundboards have been made of carbon based composite materials, such instruments commonly have poor acoustics due to an excess of high frequencies produced. This is due to carbon composites' lesser absorption of high frequencies when compared to wood. Also, carbon composites can be brittle.
Previous attempts have been made to construct soundboards of various metals, in order to achieve both durability and cheaper manufacturing costs. However, these efforts have been generally failures, as the vibrations of the metal produced a sharp and disagreeable tone quality commonly known as “metallic”. The metallic sound quality is a result of maintenance of comparatively continuous and uniform higher upper partial tones. In most metals, these tones are inharmonic secondary tones that result in a peculiar, poor quality. This poor quality arises from the comparative strength of these upper partials as related to the fundamental induced frequency. The cause of metallic sounding vibrations is described by acknowledged material science as an inherent property of most metals, a notable exception of which is aluminum.
Noticing the unique acoustical properties of aluminum, Alfred Springer obtained U.S. Pat. No. 451,863 issued on May 5, 1891. Springer discusses the use of aluminum and its alloys to manufacture the soundboards of musical instruments. Pure aluminum possesses elasticity capable of sympathetic vibration uniformly through a wide range of tone-pitch, which renders it in this respect superior to wood. Springer had constructed a prototype violin of aluminum, finding its tone to indeed be comparable to or surpassing that of highly valued older instruments. Springer's aluminum instruments also had the advantage of greater carrying power and an absence of certain imperfections in certain portions of the scale known as “wolf tones”. While pure aluminum has excellent acoustical qualities, Springer's instruments however have important shortcomings.
While pure aluminum, as conventionally manufactured, has favorable acoustical qualities, it is flimsy, weak, and easily deformed. Analysis of aluminum metal shows that conventional manufacturing techniques result in a metal composed of micron scale grains, of order a millionth of a meter in size. As conventionally manufactured with micron scale grains, pure aluminum is subject to permanent, plastic deformations, such as slippage as well as screw and edge type dislocations unless substantially alloyed. (For a brief explanation of deformations in metal, see Kittel, Charles, Introduction to Solid State Physics, seventh edition pp. 587–603.)
While Springer discusses the use of commercial aluminum alloys to satisfy strength and hardness requirements, the sound quality of the aluminum metal plates in fact becomes increasingly metallic with added alloy content. The problem with soundboards made of conventional aluminum alloys is that basic strength and durability requirements required an alloy content exceeding the amount that results in an unfavorable, metallic sound quality. (Alternatively adding extra structural supports to a soundboard would force additional acoustical nodes, preventing free vibration of the plate.) The present invention is distinguishable in that it uses nanostructured materials, such as substantially finer grained aluminum, (that may be further strengthened with composites) in musical instrument construction. Use of these materials solves materials' deficiencies of the prior art by strengthening aluminum without detriment to its acoustical properties.
Nanostructured (also known as “nanophase” and “nanocrystalline”) materials, are a new kind of material with constituent grains (crystals) that are substantially smaller than those of their conventionally manufactured counterparts. These grains are generally less than a micron and can be 1–100 nanometers in size. In nanophase materials, the smaller size constituent crystals or grains impart greater hardness, strength, and deformation resistance. (For a brief general introduction to the subject of nanophase materials, see Siegel, Richard W., Creating Nanophase Materials, Scientific American, December 1996, pp. 74–79.)
While nanophase materials are disclosed in the prior art, the use of nanophase materials for musical instruments is not. The following are relevant prior art that relate to the manufacture of articles from nanophase materials although they do not disclose the application to musical instrument construction.
U.S. Pat. No. 5,984,996 issued on Nov. 16, 1999 to Kenneth E. Gonsalves, and Sri Prakash Rangarajan, describes nanostructured metals, metal carbides and metal alloys, including the production of nanophase aluminum powders through chemical reaction and subsequent collection. The present invention is distinguishable, in that it makes use of nanophase materials for musical instruments.
U.S. Pat. No. 6,689,192 B1 issued on Feb. 10, 2004 to Jonathan Phillips, William Perry, and William Kroenke, describes a method for producing metallic nanoparticles by vaporizing an aerosol of metallic microparticles in a non-oxidizing plasma. The vapor is then directed away from the hot plasma to allow metallic nanoparticles to condense. The present invention is distinguishable, in that it makes use of nanophase materials for musical instruments.
U.S. Pat. No. 6,740,287 B2 issued on May 25, 2004 to Romain L. Billiet and Hanh T. Nguyen, describes a multi step method for method for making metal articles from nanoparticulate material. The present invention is distinguishable, in that it makes use of nanophase materials for musical instruments.
U.S. Pat. No. 6,706,324 B2 issued on Mar. 16, 2004 to Srinivasan Chandrasekar, Walter D. Compton, Thomas N. Farris, and Kevin P. Trumble, describes a procedure for obtaining metals that include nanophase microstructures (grains). The nanocrystalline microstructures are obtained by strain deformation resulting from mechanical machining of metal into small chips, particles, ribbons, or platelets. The resulting chips are then used in forming an article of metal. The present invention is distinguishable, in that it makes use of nanophase materials for musical instruments.